This invention relates generally to adaptive antenna systems which, for example, could be used to track moving objects. The classic and well known approach to this tracking problem is to provide a dipole antenna in combination with a parabolic reflector and to mechanically rotate this combination to scan the relevant portion of space. Such mechanical scanning schemes have a number of obvious drawbacks. Scan rate is inherently slow. The apparatus is generally bulky. The mechanical drive arrangement may introduce inaccuracies, is subject to wear and impaired operation during inclement weather, and does not physically conform to the surface on which it is mounted, thus requiring a radome covering for aircraft installation thereby impairing aerodynamic performance.
A substantial improvement over the mechanically driven antenna arrangement is represented by U.S. Pat. Nos. 3,036,210 to Lehan et al. and 3,251,062 to Ghose which disclose an electronically scanning antenna employing plural phase locked loops to produce optimum directivity. While the Lehan et al. patent represents a substantial improvement over the previous prior art, it involves an extensive and rather complex electrical system for even a very small number of antenna elements.